The present invention relates to passive apparatus and methods used to secure, lock, grab, grip or otherwise hold a desired object relative to a work surface. More particularly, the present invention relates to such apparatus and methods exhibiting six degree of freedom movement, and operable as controlled by a single command signal. As used herein, the term "passive" means that independent means, external to the apparatus, must be used to place or position the apparatus in a desired position prior to activating the single command control that locks it in the desired position.
A common and well known example of a passive clamping apparatus is a pair of pliers, having jaws at one end that move in and out as controlled by applying manual forces to handles at the other end. Numerous configurations and styles of pliers are known in the art.
Another common type of passive clamping apparatus is a vice, having jaws that selectively move to a closed or open position as controlled manually through the use of a lead screw or equivalent mechanism that moves one jaw relative to the other. As with the pliers, there are numerous styles and configurations of vices known in the art. U.S. Pat. No. 709,399, for example, illustrates a six-degree of freedom vice having mechanical movement capabilities, as follows: (1) up/down; (2) in/out; (3) tilt or pitch; (4) rotation; (5) yaw; and (6) jaws in/out.
Frequently, there is a need in the art for a work holder that is readily positioned in a desired location and orientation, e.g., manually, and then locked in that position through the application of a suitable locking force, thereby allowing work to be performed on the work piece being thus held while maintaining such work piece in the desired position and orientation. U.S. Pat. No. 4,564,179 discloses one type of such a work holder. In the '179 patent, for example, the work holder includes a plurality of articulated arms that allow a clamp to be manually positioned in any plane and position. When a user selects the desired position, hydraulic pressure is applied simultaneously to all of the articulated joints to lock them, from a single control. The hydraulic pressure is applied from a central cylinder to each joint via a separate hydraulic line. As such, each joint locks simultaneously.
Some applications for using a work holder, however, such as where the positioning of the work piece must be very precise, may require that the joints of the multi-joint work holder be locked in a prescribed sequence. For such an application, the prescribed locking sequence is achieved by applying the requisite locking forces to each joint in the desired sequence, thus necessitating a separate control line for each joint, and an associated control system for generating or controlling the forces that are to be directed to each joint in the correct sequence and timing relationship.
Still other applications for using a work holder, or similar passive clamping or grabbing apparatus, require that the grabbing apparatus be at a location remote from or inaccessible to an operator or user. For such remote or inaccessible use, it is desirable to simplify the linkage between the user and the grabbing apparatus. Unfortunately, however, if the grabbing apparatus includes multiple joints, and if it is desired to lock the joints in a prescribed sequence, the linkage and associated controls tend to become more complex, rather than simpler. Thus, there is a need in the art for a multi-joint grabbing apparatus that can be used remotely from an operator for tasks requiring a prescribed locking sequence of its joints that provides a simple control linkage from the operator to the apparatus.
Other uses of a passive clamping or grabbing apparatus also require precise locking capabilities and a simple control linkage. For example, in the use of remotely operated vehicles, there is typically provided one or more manipulators, e.g. robotic arms, designed to perform a variety of robotic tasks. Placed on such vehicles within reach of such manipulators there is typically found a platform or tray on which various tools are carried. These tools are used to assist a manipulator as it performs an assigned task. Many of these remotely performed tasks require that the vehicle and its work platform be properly stabilized or anchored before such tasks can be carried out. Such stabilization has heretofore been achieved by using at least one manipulator to clamp the workstation to a desired anchor or other support while the task is performed. Unfortunately, using a manipulator for this anchoring or stabilizing function ties up the manipulator, thereby preventing it from being used for other purposes, even though it has the capability of performing a wide variety of complex robotic tasks that far exceed its functioning as an anchor or stabilizer. What is needed, therefore, is a clamping or grabbing tool that can be used in conjunction with the robotic manipulators of a remotely operated vehicle, or similar robotic device, for stabilizing the vehicle or device and its work platform, and freeing up the manipulators for other tasks better suited to their capabilities.
The present invention advantageously addresses the above and other needs.